1. Field of the Invention
The present invention relates to motor vehicle chassis, and in particular to a side intrusion beam within a door which is structurally integrated with the chassis.
2. Discussion of the Prior Art
It has been previously proposed to structurally integrate a vertically sliding door into a vehicle chassis. This Door And Chassis Integration Technology (DACIT) as applied to vertically sliding doors is disclosed in the following U.S. Patents issued to John A. Townsend, incorporated herein by reference: U.S. Pat. No. 4,801,172 issued Jan. 31, 1989; U.S. Pat. No. 4,940,282 issued Jul. 10, 1990; U.S. Pat. No. 5,378,036 issued Jan. 3, 1995; and application Ser. No. 08/328,124 filed Oct. 20, 1994.
In operation, when the vertically sliding door which is the subject of the above patents is closed, structural key members located on the edges of the door engage with mating receptacles in the door jambs. In this position, each key member and mating receptacle pair is able to transmit compressive, tensile and torsional forces between the door and the vehicle chassis. The gap in the vehicle chassis structure that is created by the door opening is bridged by the door when it is in the closed position. This integrated chassis system that exists when the doors of the vehicle are closed provides a much stiffer vehicle frame and more fully surrounds the vehicle occupants to protect them from front, rear and side impact. The last issued patent above also teaches the use of a single, flat, side intrusion beam spanning across the door to inhibit intrusion to the vehicle during a side impact collision.
In a manner similar to that above, it has also been proposed to apply DACIT to conventional hinged vehicle doors. This concept is taught by the present inventor in U.S. application Ser. No. 08/577,649, filed Dec. 22, 1995, incorporated herein by reference. That application also discloses the use of two horizontal beams that span between the structural connections located adjacent to the four corners of the door. However, since no structural framework is located across the central portion of the door, the vehicle occupants are not fully protected from side impact intrusion.
Another example of a prior are side intrusion beam is shown in U.S. Pat. No. 3,887,227 issued to Deckert on Jul. 3, 1975. This apparatus employs tension members within a vehicle door that are tied to opposite sides of the door opening when the door is closed. However, these tension members only transmit tensile forces and are not capable of transmitting compressive or torsional forces across the door openings, which would be needed to reduce structural deformation during a front or rear end collision. These tension members also only cover a narrow portion of the door opening. Therefore, they may be wedged upward or downward by an impinging vehicle and may only provide limited protection in some collisions.
The above prior art side intrusion beams do not curve outward or inward as they span across the doorway, they have flat cross-sections, and they do not cover a large portion of the door. The prior art provides limited protection from intrusion during a side impact collision. Using the construction features of the prior art to create a door with increased intrusion protection would yield a door having increased weight and cost. Increasing the weight of a moving door and the overall weight and cost of a vehicle is often an unacceptable option in vehicle manufacture, and therefore a lower level of side intrusion protection is chosen instead.
What is needed and is not provided by the prior art is a side intrusion beam that efficiently provides a high level of side intrusion protection without adding excess weight, cost, size or complexity to the vehicle door.